Linear association between maternal age and spontaneous breech presentation in singleton pregnancies after 32 weeks gestation

Fetal size at the 32nd gestational week is associated with the risk of breech presentation at term birth

OBJECTIVES

The association patterns between breech presentation at birth and fetal biometry at the first, second, and third trimesters, newborn size but also maternal age, body height, prepregnancy weight status as well as gestational weight gain, were analyzed using a dataset of 4501 singleton term birth in Vienna, Austria.

METHODS

In this medical record-based study, fetal biometry was reconstructed based on the results of three ultrasound examinations conducted at the 11th/12th, 20th, and 32nd gestational weeks. Head dimensions, abdominal dimensions, and femur length were determined by sonography. Birth weight, birth length, and head circumference were measured immediately after birth.

RESULTS

The total breech presentation rate at birth was 6.2%. Breech newborns were significantly (p < 0.001) shorter and lighter at the time of birth, their head circumferences, however, were significantly larger (p = 0.001). At the 32nd week, breech fetuses showed significantly smaller biparietal breadths, but highly significantly longer heads. Their abdominal dimensions were significantly smaller, and their femora were shorter. Higher maternal age, and a longer, but narrower fetal head as well as smaller abdominal dimensions at the 32nd gestational week were independently related to a higher risk of breech presentation at the time of birth.

CONCLUSIONS

Fetuses who remain in a breech presentation until term birth (≥37 gestational weeks) differed significantly in head and abdominal dimensions from cephalic fetuses from the 32nd gestational week onwards.

[Breech Presentation: CNGOF Guidelines for Clinical Practice - Epidemiology, Risk Factors and Complications]

OBJECTIVES

To study the frequency, the risk factors and the mode of delivery of breech presentation. To analyze the perinatal morbidity and mortality associated with breech presentation in comparison to cephalic presentation from all mode of delivery.

METHODS

MedLine and Cochrane Library databases search in French and English and review of the main foreign guidelines between 1980 and 2019.

RESULTS

Three modes of breech presentation exist according to fetal lower limbs position: frank in 2/3 of cases, complete in 1/3 of cases or, more rarely, incomplete (LE3). About 5% of women gave birth in breech presentation in France (LE3). As the frequency of breech presentation decreases with increasing gestational age, this incidence is lower after 37 WG and represents only 3% of term deliveries (LE3). Congenital uterine malformation (LE3) and fibroma (LE3), prematurity (LE3), oligoamnios (LE3), some fetal congenital malformations (LE3) and low birthweight for gestational age (LE3) are the main risk factors with breech presentation. In France, one-third of women with a term fetus in breech presentation attempt a vaginal delivery (LE3), which is successful in 70% of cases (LE3). Neonatal outcome is not associated with type of breech presentation (frank or complete) in case of vaginal delivery attempt after 37 WG (LE3). Overall, perinatal morbidity and mortality after 37 WG of breech presentation appear to be greater than in cephalic presentation from all mode of delivery (LE3). The risk of traumatic injury in breech delivery is estimated under 1% (LE3). The most common injuries are collarbone fractures, hematomas or contusions, and brachial plexus injury (LE3). Breech presentation is associated with an increased risk of hip dysplasia (LE3) and cesarean delivery does not seem to be a protective factor (LE3). Breech presentation does not appear to be associated with an increased risk of cerebral palsy compared to cephalic presentation after exclusion of fetuses with congenital malformations (LE3).

CONCLUSION

Worldwide, mode of delivery of breech presentation has undergone profound changes since the publication of the TBT (Term Breech Trial). There are intrinsic factors associated with breech presentation, which should not be overlooked when interpreting the increased perinatal morbidity and mortality observed in case of breech presentation.

Linear association between maternal age and need of medical interventions at delivery in primiparae: a cohort of 21,235 singleton births

OBJECTIVES

We sought to investigate the potential association between maternal age and the need for active obstetrical intervention intrapartum in primiparas.

STUDY DESIGN

Observational study over 14 years (2001-2014) of all consecutive primiparous singleton births having delivered at the Centre Hospitalier Universitaire Hospitalier Sud Reunion's maternity (French overseas department, Indian Ocean).

RESULTS

Of the 21,235 singleton primiparous births, there were three significant linear associations between maternal age from 12 years of age to 42 + (all χ² for linear trend, p < .0001) (a) vaginal deliveries without any medical intervention, (b) rate of cesarean sections, and (c) rate of operative vaginal procedures. These three linear associations persisted when controlling for maternal obesity (±30 kg/m²), "heavy babies" (>3.5 kg), and ethnicity. Using maternal age remained significantly an independent risk factor (p < .0001), after controlling for the major confounders: maternal BMI, maternal height, birthweight ≥3500 g, p < .0001.

CONCLUSIONS

Increasing maternal age has a linear association with vaginal deliveries without any medical intervention, rate of cesarean sections, and rate of operative vaginal procedures. These associations are independent of maternal BMI and maternal height. We currently do not have a specific explanation why younger women appear to be protected from requiring intrapartum obstetric intervention. Nevertheless, these strong facts deserve acknowledgement and further research.